Phenolic
acids are plant metabolites widely spread throughout the plant kingdom. Recent interest in phenolic acids stems from
their potential protective role, through ingestion of fruits and vegetables,
against oxidative damage diseases (coronary heart disease, stroke, and cancers). Phenolic compounds are essential for the growth and
reproduction of plants, and are produced as a response for defending injured
plants against pathogens. The importance of antioxidant activities of phenolic
compounds and their possible usage in processed foods as a natural antioxidant
have reached a new high in recent years.

Absorption
The absorption and bioavailability of phenolics in humans are controversial. Data on these aspects of phenolics
are scarce and merely highlight the need for extensive investigations of the
handling of phenolics by the gastrointestinal tract and their subsequent
absorption and metabolism.

Rocz Panstw Zakl Hig. 2013. Digestion and absorption of
phenolic compounds assessed by in vitro simulation methods. A review. Phenolic
compounds are a group of key plant metabolites found abundantly in fruit and
vegetables. Because of their antioxidant properties, they play a significant
role in preventing various degenerative illnesses, tumours or cardiovascular
disease. In nature, they are present in foods mainly as esters, glycosides and
polymers which need to undergo enzymatic hydrolysis in the digestive tract or by
the gut microflora before becoming absorbed. The biological properties of these
phenolic compounds undergoing this degradation, are thus governed by their
absorption as well as metabolism. Many methods are used to assess the rates and
the degrees to which these substances are digested and absorbed, both in vivo
and in vitro ones, where the former are the most reliable, although they suffer
from various limitations. For this reason, many in vitro models have now arisen
to simulate the function of human digestion in the attempt to faithfully
re-create real-life conditions. Mechanisms of polyphenols absorption have been
principally studied by intestinal epithelial cell models, in particular, those
using the Caco-2 cell line.

Phenolics in Plants
Phenolic acid compounds seem to be universally distributed in plants.
They have been the subject of a great number of chemical, biological,
agricultural, and medical studies. They form a diverse group that
includes the widely distributed hydroxybenzoic and hydroxycinnamic acids.
Hydroxycinnamic acid compounds occur most frequently as
simple esters with hydroxy carboxylic acids or glucose
Hydroxybenzoic acid compounds are present mainly in the
form of glucosides.

Cancer fighting propertiesFood Chem. 2013. Cytotoxic impact of phenolics from Lamiaceae species on
human breast cancer cells. Wrocław Medical University, Department of Medical
Biochemistry, Chałubińskiego Wrocław, Poland.
The aim of this study was to evaluate the cytotoxicity of dried aqueous extracts
from Thymus serpyllum (ExTs), Thymus vulgaris, Majorana hortensis (ExMh), and
Mentha piperita (ExMp), and the phenolic compounds caffeic acid (CA), rosmarinic
acid (RA), lithospermic acid (LA), luteolin-7-O-glucuronide (Lgr),
luteolin-7-O-rutinoside (Lr), eriodictiol-7-O-rutinoside (Er), and arbutin (Ab),
on two human breast cancer cell lines: Adriamycin-resistant MCF-7/Adr and
wild-type MCF-7/wt. In the MTT assay, ExMh showed the highest cytotoxicity,
especially against MCF-7/Adr, whereas ExMp was the least toxic; particularly
against MCF-7/wt cells. RA and LA exhibited the strongest cytotoxicity against
both MCF-7 cell lines, over 2-fold greater than CA and Lgr, around 3-fold
greater than Er, and around 4- to 7-fold in comparison with Lr and Ab. Except
for Lr and Ab, all other phytochemicals were more toxic against MCF-7/wt, and
all extracts exhibited higher toxicity against MCF-7/Adr. It might be concluded
that the tested phenolics exhibited more beneficial properties when they were
applied in the form of extracts comprising their mixtures.

Phenolic acids
and cholesterol
Drinking a cup of coffee induces an increase in the resistance of LDL
cholesterol to oxidative changes, probably as a result of the incorporation of
phenolic acids found in coffee into LDL cholesterol.

Chemistry
Plant phenolic compounds are diverse in structure but are characterised
by hydroxylated aromatic rings (e.g. flavan-3-ols). They are categorised as
secondary metabolites, and their function in plants is often poorly understood.
Many plant phenolic compounds are polymerised into larger molecules such as the
proanthocyanidins (PA; condensed tannins) and lignins.
Furthermore, phenolic acids may occur in food plants as esters or
glycosides conjugated with other natural compounds such as flavonoids, alcohols,
hydroxyfatty acids, sterols, and glucosides.

Phenols
Phenols, sometimes called phenolics, are a class of chemical compounds
consisting of a hydroxyl functional group (-OH) attached to an aromatic
hydrocarbon group. The simplest of the class is phenol (C6H5OH). Some phenols
are germicidal and are used in formulating disinfectants. Others possess
estrogenic or endocrine disrupting activity.

Phenolic compounds Phenol, the parent compound, used as an disinfectant and for chemical synthesis.
Polyphenols like the
flavonoids and tannins.
Capsaicin, the pungent compound of
chilli peppers. Tyrosine, an amino acid.
Tyrosol found in olive oil
Q. Does anyone know where I can purchase tyrosol capsules /
tincture ? Cannot seem to locate a source. Tyrosol has also been found to
protect cells of the central nervous system from dying after exposure to toxins
like glutamate (MSG and artificial sweeteners). And because itís neuroprotective,
tyrosol is being studied as a beneficial treatment for Alzheimer's, Parkinson's
and other diseases.
A. This phenol antioxidant is, to my knowledge, not yet available
as a supplement as of 2014.
The neurotransmitters
serotonin,
dopamine, adrenaline, and noradrenaline.
L-DOPA, a drug to treat Parkinson's disease.
Eugenol, the main constituent of the essential oil of
clove.
Chavibetol from betel.
Estradiol and other estrogens. Scientists have formulated the 'phenolic A ring
hypothesis' for the neuroprotective effects of estrogens based upon several
observations: (i) structure-activity relationships show that a phenolic A ring
and at least two additional rings are required for neuroprotection while
estrogenicity requirements are more stringent; (ii) neuroprotection with
phenolic A ring compounds occurs in cells that lack estrogen receptors and are
not antagonized by anti-estrogens; (iii) phenolic A ring compounds rapidly
activate a variety of signal transduction pathways that are known to be involved
in cell homeostasis; and (iv) in vivo, treatment with estrogens results in a
neuronal type-independent neuronal protection from ischemic insult. Potential
mechanisms of actions that may be involved in the neuroprotective effects of
phenolic A ring compounds are: (i) estrogen redox cycling that potently inhibits
oxidative stress; (ii) interactions with signal transduction pathways including
the transcription factor cAMP response element binding protein; and (iii)
induction of anti-apoptotic proteins. These signaling pathways may individually
or collectively contribute to the plethora of neuronal cell types that are
protected from a variety of insults by estrogen-like compounds.
Methyl salicylate, the major constituent of the
essential oil of wintergreen.
Raspberry ketone a compound with an intense raspberry smell. Salicylic acid is a
phenolic compound
Gallic acid, found in gallnuts.Ellagic acid
Thymol (2-Isopropyl-5-methyl phenol), an antiseptic that is used in mouthwashes.
BHT (butylated hydroxytoluene), a fat-soluble antioxidant and food additive.
... and many more.

Natural Substances with Phenolic acidsPropolis is one of the few natural remedies that has maintained its
popularity over a long period of time. The pharmacologically active
molecules in the propolis are flavonoids and phenolic acids and their
esters. These components have multiple effects on bacteria, fungi and
viruses. In addition, propolis and its components have anti-inflammatory
and immunomodulatory activities. Moreover, propolis has been shown to
lower blood pressure and cholesterol levels. However, clinical studies to
substantiate these claims are required.

Phenolic
Acids in Berries
The composition of phenolic acids in several small berries grown in
Northeastern Poland, namely, low-bush blueberries, black mulberries,
European juneberries,
black currants, fruits of blue-berried honeysuckle, and blackberries.
The total content of phenolic acids ranged from 2845 (black mulberries) to
5418 (blue-berried honeysuckle). Twenty phenolic acids were identified in
the berries. Of these, hydroxycaffeic, m- and p-coumaric, and
3,4-dimethoxycinnamic acids were the major phenolic acids in blackberries
and blueberries, m-coumaric acid was the major phenolic acid in
blue-berried honeysuckle and black currant fruits, while salicylic,
caffeic, and m- and p-coumaric acids were the predominant phenolic acids
in European juneberries. Syringic and veratric acids were detected only in
blueberries, while p-hydroxybenzoic and sinapic acids were present only in
black currants and o-coumaric acid was present in blueberries and black
mulberries.

Spices contain phenolic substancesSpices are
known to significantly contribute to the flavor, taste, and medicinal
properties of food because of phenolics. Most spices contain phenolic
acids such as tannic, gallic, caffeic, cinnamic, chlorogenic, ferulic and
vanillic acids. A high amount of tannic and gallic acids are found in
black mustard and clove. Caffeic, chlorogenic and ferulic acids are found
in a good amount in cumin. Vanillic and cinnamic acids are found in onion
seeds.

Others
Cannabinoids, the active constituents of Cannabis.
Cresols from coal tar and creosote.
Guaiacol (2-methoxyphenol) from roasted coffee, whisky, and smoke that has a
smoky flavor.
Salicylic acid, a plant hormone and analgesic, antipyretic, and
anti-inflammatory drug, precursor compound to Aspirin.
Aspirin (acetylsalicylic
acid) is still the most commonly used salicylate. After oral
administration as an aqueous solution aspirin is rapidly absorbed at the
low pH of the stomach millieu. Less rapid absorption is observed with
other formulations due to the rate limiting step of tablet disintegration
- this latter factor being maximal in alkaline pH. The rate of aspirin
absorption is dependent not only on the formulation but also on the rate
of gastric emptying. Aspirin absorption follows first-order kinetics with
an absorption half-life ranging from 5 to 16 minutes. Hydrolysis of
aspirin to salicylic acid by nonspecific esterases occurs in the liver
and, to a lesser extent, the stomach so that only 68% of the dose reaches
the systemic circulation as aspirin. Both aspirin and salicylic acid are
bound to serum albumin (aspirin being capable of irreversibly acetylating
many proteins), and both are distributed in the synovial cavity, central
nervous system, and saliva. The serum half-life of aspirin is
approximately 20 minutes. The fall in aspirin concentration is associated
with a rapid rise in salicylic acid concentration. Salicylic acid is
renally excreted in part unchanged and the rate of elimination is
influenced by urinary pH, the presence of organic acids, and the urinary
flow rate. Metabolism of salicylic acid occurs through glucuronide
formation (to produce salicyluric acid), and salicyl phenolic glucoronide),
conjugation with glycine (to produce salicyluric acid), and oxidation to
gentisic acid.
Orthophenyl phenol , a fungicide used for waxing citrus fruits.
The pH indicators phenolphthalein, phenol red, bromothymol blue, thymolphthalein,
and bromophenol blue.
Psilocin, a hallucinogenic alkaloid of Psilocybe mushrooms.

Phenolic Compounds in Herbs
There are countless herbs that have phenolic compounds, here is one example:
Phenolic components and antioxidant activity of Fernblock, an aqueous extract of
the aerial parts of the fern
Polypodium leucotomos.
Methods Find Exp Clin Pharmacol. 2006.
Fernblock, an aqueous extract of the aerial parts of the fern Polypodium
leucotomos is used as raw material for topical and oral photoprotective
formulations. Phenolic compounds were identified as 3,4-dihydroxybenzoic acid,
4-hydroxybenzoic acid, vanillic acid, caffeic acid, 4-hydroxycinnamic acid,
4-hydroxycinnamoyl-quinic acid, ferulic acid, and five chlorogenic acid isomers.

Questions
What does this mean? "Drinking a cup of coffee induces an increase in
the resistance of LDL cholesterol to oxidative changes, probably as a result of
the incorporation of phenolic acids found in coffee into LDL cholesterol. That
caffeine coffee is good or bad? Thanks, got it off your website on phenols."
Phenolic acids found in coffee act as antioxidants and are good.
Studies show a cup or two of coffee is beneficial but too much caffeine may not
be healthy.